Despite near-universal calls for swift action to revive America's sinking economy, congressional leaders of both parties say it is doubtful that a major stimulus package will be awaiting Barack Obama's signature when he is sworn in as president on January 20.

Just days into the New Year, U.S. legislators are tamping down expectations for what many Democrats had urged a few weeks ago: that Congress act upon Mr. Obama's call for a massive economic recovery program before his presidential term begins.

"It is going to be very difficult to get the package put together that early so that it can have sufficient time to be reviewed, and then sufficient time to be debated and passed," said Steny Hoyer.

Senate Minority Leader Mitch McConnell expressed similar skepticism. Speaking on ABC's This Week program, the Kentucky Republican said he hopes Congress will allow bipartisan input concerning what is expected to be the largest economic-stimulus package in U.S. history.

"I think at least [congressional hearings], and some kind of bipartisan consideration, would be helpful," said Mitch McConnell. "What I worry about is the haste with which this may be done. This is an enormous bill - it could be close to a trillion-dollar spending bill."

President-elect Obama is calling for hundreds of billions of dollars in federal spending to spur job creation through initiatives focusing on infrastructure, energy efficiency, education and health-care reform. Most Republicans have not ruled out such initiatives, but many have expressed a preference for cutting taxes over boosting spending.

Although Democrats will have expanded majorities in the new Congress, they will fall just short of the supermajority that would allow them to break Republican filibusters - a parliamentary maneuver often used by minority-party senators to block legislation.

But Illinois Senator Dick Durbin, a close political ally of the president-elect, says Democrats have no intention of shutting out Republicans when it comes to crafting the stimulus package.

"We cannot pass the economic recovery plan that this nation desperately needs without bipartisan cooperation," said Dick Durbin. "We have got to put aside a lot of the squabbling of the past and come together under this new administration and new leadership to get the American economy back online."

The U.S. economy is believed to have been in a recession for more than a year, hammered by a housing meltdown that provoked a devastating credit squeeze. At the same time, America's national debt has risen to record-highs.

President-elect Obama says, in the long term, the United States will have to put its fiscal house in order, but that for now, further deficit spending will be required to restore economic growth.